Plating process enhanced by squeegee roller apparatus

ABSTRACT

An improved apparatus for treating plate-like work pieces with a designated chemical solution, including printed circuit boards, including (1) a tank for holding the chemicals, agitation frame and roller assembly, (2) a frame that holds two rollers covered in brush or sponge like material, (3) a guide rail assembly attached to a roller frame, (4) a slotted block attached to a guide rail (5) a disk with a bottom shaft coupling and top pin to move slotted block, (6) a low rpm motor that attaches to disk coupling.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to equipment for coating and electroplating objects. More particular, this invention relates to an apparatus for coating and electroplating objects such as printed circuit boards.

2. Description of the Related Art

The plating of objects such as printed circuit boards (PCBs), maybe accomplished by various processes. For PCBs having various holes, an initial step is required to provide a conductive electrical path on the whole surface.

This metal deposition process often called “electroless plating”, does not rely on the typical electric fields associated with electroplating. Therefore, this metal deposition step is generally harder to control than a regular electroplating process.

Since it is impossible to build up a desired level of metal with this process, the object is moved to an electroplating process for additional build up of conductive material to the surface and holes of the object.

In a standard deposition process, the object to be coated is immersed into various chemical solutions. The tanks, which hold these solutions, have open tops to allow work to be placed inside vertically (i.e., with their printed surfaces and direction of the axis of their holes facing sideward).

One of the most commonly used electroplating processes for adding conductive material to objects is an electrolyte plating type process. It involves an open tank filled with plating solution or electrolyte.

These tanks sometimes include electrodes where a voltage is applied to set up an electric field in the tank. A power supply that has a variable voltage and amperage control is used to create the voltage between the electrodes

The object to be plated is called the cathode, It is attached to the negative side of the power supply. The other electrode, called the anode, is attached to the positive terminal of a power supply.

The electrolyte consists of chemicals, usually a metal dissolved and suspended in a liquid as a metal ion. When the electric field is applied, the metal ions deposit on the cathode and increase its thickness over time until the process is halted or the solution is exhausted. If the liquid has no movement or agitation the rate of metal ion deposition will slow down by an order of magnitude unless the electrolyte is agitated or some other means is used to deliver fresh electrolyte.

Agitation is also used to dislodge and sweep away hydrogen gas bubbles that form on plating objects. Also it is used as a means to move electrolyte into sideward holes.

Thus it often proves to be the case that such electroplating process have the same disadvantages as previously seen for the metal deposition process, i.e., their capabilities are limited when it comes to depositing conductive coatings on objects in a vertical tank, with sideward facing holes to be plated.

Because off these disadvantages there exists a continuing need for improved metal deposition and electroplating methods and apparatus.

3. Objects and Advantages

There has been summarized above, rather broadly, the prior art that is related to the present invention in order that the context of the present invention may be better understood and appreciated. In this regard, it is instructive to also consider the objects and advantages of the present invention.

It is an object of the present invention to provide an apparatus that yields more efficient plating of objects.

It is an object of the present invention to provide an apparatus that electroplates tiny sideward facing holes, e.g., printed circuit boards.

It is an object of the present invention to provide an apparatus for eliminating chemical air agitation units that are harmful to people and the environment.

It is an object of the present invention to provide an apparatus that selectively plates more inside the hole than surface of the objects, e.g., PCBs.

These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying summary, drawings and the detailed description that follows.

SUMMARY OF THE INVENTION

The present invention is generally directed to satisfying the needs set forth above and overcoming the limitations and problems identified with prior metal deposition and electroplating processes that utilize vertical tanks.

In accordance with one preferred embodiment, the present invention takes the form of an apparatus for treating plate-like pieces with a designated chemical solution, including printed circuit boards.

This apparatus includes: (1) a tank for holding the chemical solution, which is configured to receive a vertically oriented work piece, (2) a conductive plating rack configured to receive and mount the work piece so that the work piece may act as a cathode when the rack is immersed in the tray and surrounded by an electrolytic solution. (3) a sponge type material covering a roller assembly, with a frame to which the rollers are attached and able to move freely, (5) a guide rail attached to a roller assembly, (6) a disk with attachment pin that travels between slotted guide block that connects to guide rails for roller assembly movement, (7) a low rpm motor that is attached with a cam to a disk for guide block travel between disk pin.

There has been summarized above, rather broadly, the present invention in order that the detailed description that follows may be better understood and appreciated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a perspective view of the tank assembly used with a preferred embodiment of a plating apparatus of the present invention.

FIG. 2 illustrates a roller assembly adjustment for use between objects to be plated.

FIG. 3 illustrates a roller guide or block used to hold support rail in place.

FIG. 4 illustrates a roller core fabricated from plastic or inert conductive material with bushings and a sponge like material covering for use with the present invention.

FIG. 5 illustrates a tank assembly used for multiple objects to be plated.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purpose of explanation and not limitation, specific details are set forth below in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well known methods hardware, ect. are omitted so as not to obscure the description of the present invention with unnecessary detail.

referring now to the drawing which show a preferred embodiment of the present invention and wherein like reference numerals designate like elements throughout.

FIG. 1 is seen to provide a perspective view of a key aspect of a preferred embodiment of the plating method of the present invention for treating thin, porous, plate-like work pieces (e.g., PCB).

The materials to be treated, which for illustrative purposes we take to be PCBs 2, are positioned vertically. FIG. 1 illustrates a clamping device 3, having thumb screws 3 a, which is suitable for this purpose. Roller assembly frame 4 is used to hold roller core 5 which is fabricated from plastic or conductive inert or soluble material held securely in place.

The roller assembly is then transported back and forth by means of a motor 6 attached to a disk 7 with an adjustable pin 8 on top is a slotted travel block 9 which connects to a guide bar 10, attached to an additional top guide bar 11 that travels between guide block 12. The guide bars are connected to the roller frame 4.

Because of the different types and thickness of objects to be plated there is an adjustable roller gauge 13 to compensate for varying board thickness or roller material 14 thickness.

To further improve the travel of the guide rail assembly a guide block will be used 15 with a free moving travel wheel. Additionally bushings 17 will be added into roller core at either end to allow spinning. Roller will be covered with PVA sponge like material or polypropylene that acts as a brush and squeegee to coat surface and interior of object.

In another preferred embodiment of the present invention, a large tank with a dual roller assembly 18 will be used for multiple object coating. 

1. An apparatus for treating plate-like work pieces with a designated chemical solution. Including printed circuit boards, said apparatus comprising: A tank for holding said chemicals, an agitation frame with roller assembly, said tank having an open top which is configured to receive said work piece when said work piece is oriented so that its largest-surface area is oriented vertically.
 2. An apparatus as recited in claim 1, further comprising: A clamping device for electrical connection and aligning work piece surface.
 3. An apparatus as cited in claim 1 further comprising a roller brush assembly configured to travel between said work piece.
 4. An apparatus cited in claim 3, that further includes a roller core that is conductive and acts as an anode for producing an electric field.
 5. An apparatus as cited in claim 3, wherein said roller brush assembly is attached to a guide rail that is moveable and allows travel back and forth.
 6. An apparatus as cited in claim 5, wherein a guide rail is attached to a slotted block that rides between a pin.
 7. An apparatus as cited in claim 6, wherein a circular disk with a pivot pin is mounted on top coupled to a low rpm adjustable motor to drive slotted block and rail assembly. 